Naval tactical picture compilation is a task for which allocation of attention to the right information at the right time is crucial. Performance on this task can be improved if a support system assists the human operator. However, there is evidence that benefits of support systems are highly dependent upon the systems’ tendency to support. This paper presents a study into the effects of different levels of support conservativeness (i.e., tendency to support) and human competence on performance and on the human’s trust in the support system. Three types of support are distinguished: fixed, liberal and conservative support. In fixed support, the system calculates an estimated optimal decision and suggests this to the human. In the liberal and conservative support types, the system estimated the important information in the problem space in order to make a correct decision and directs the human’s attention to this information. In liberal support, the system attempts to direct the human’s attention using only the assessed task requirements, whereas in conservative support, the this attempt is done provided that it has been estimated that the human is not already paying attention (more conservative). Overall results do not confirm our hypothesis that adaptive conservative support leads to the best performances. Furthermore, especially high-competent humans showed more trust in a system when delivered support was adapted to their specific needs.